Tritone substitution: Gb7 can be replaced by C7 (a tritone away). Both chords share the same tritone between the 3rd and 7th, resolving to the same tonic.
The augmented 9th is enharmonically equivalent to a minor 3rd and sounds alongside the chord’s major 3rd. Their chromatic clash creates sharp tension characteristic of blues and rock.
Application
Blues rock (Jimi Hendrix "Purple Haze")
Funk
Jazz fusion
Voicing & structure
Root position
v1Gb(Gb4)Bass
root
v2Bb(Bb4)M3from Gb
v3Db(Db5)m3from Bb
v4Fb(Fb5)m3from Db
v5A(A5)P4from Fb
Harmony
Compatible scales
All chord tones are contained in these scales — use them for improvisation.